Thursday, April 28, 2011

NASA's space shuttle program will soon be coming to an end, after 30 years and 135 missions to low-Earth orbit. The "final" launch tomorrow of the shuttle Endeavor will mark the second "final" launch this year (after the "final" launch of Discovery in February), with the third and final "final" launch of Atlantis planned for June. The retirement homes for the aging shuttles have already been selected, and flocks of tourists are gathering in Florida to witness the penultimate launch. Like the history of the shuttle program itself, the event is driven more by public relations than by science.

Consider the Hubble Space Telescope, one of the landmark public relations achievements of the space shuttle program. Released into low-Earth orbit from the cargo bay of the shuttle Discovery in April 1990, it was soon determined to have blurry vision which was subsequently corrected during the first servicing mission in December 1993. Various shuttles returned for additional servicing missions in February 1997, December 1999, March 2002, and finally in May 2009. It made great television. Heroic astronauts performed difficult tasks while floating 350 miles above our stunning blue planet. I don't mean to marginalize their achievements. It's just that low-Earth orbit is a lousy place to do science.

The only scientific advantage of low-Earth orbit is safety. A telescope that flies well within the protective magnetic field of the Earth is less vulnerable to charged particles from the Sun that could damage sensitive scientific instruments. The price for this safety is an endless 96-minute loop around the planet punctuated by enormous temperature variations between daylight and darkness, staggering levels of scattered light from the surface of the globe, and occasional journeys through the South Atlantic Anomaly -- a distortion in the Earth's magnetic field over South America that disrupts the normal functioning of crucial electronics. It is far better to put a telescope in an Earth-trailing orbit around the Sun like the Kepler mission, or near one of the Sun-Earth Lagrange points like the SoHO and Planck missions.

This isn't rocket science -- NASA knows that there are better places to do science than low-Earth orbit, which is why the James Webb Space Telescope will be parked at the outer Lagrange (L2) point. With the shuttles retiring and Hubble in the final phase of its mission, will the public relations gravy train come to a halt? Don't worry NASA, you still have the International Space Station.